Bite Marks
by CJS51703
Summary: Alphys is determined to make Undyne hers. And she has the perfect way to do so... (Swapfell AU)


*****Oh my God, you guys...after near two and a half years, this marks story number forty on the list! I'm so thankful for all of you guys' support, and so thankful that I've gotten here. Sappy stuff aside, this is a full-well test run of Swapfell. So, I may get some characterization wrong. After that extended note, Swapfell doesn't belong to me, Alphys and Undyne belong to Toby Fox, the story plot belongs to me, and let's begin!**

 _Journal Entry 0312:_

 _Today, I learned that humans and monsters alike need their kidneys to survive. You learn something new every day, I guess. What I've also learned is that I should put my experiments under before I begin to work. It's less fun that way, but their screaming before they pass out from the pain gives me an awful headache._

Undyne put down her pencil, massaging her temples in hopes of easing her pain. At last, she reached into a drawer in her desk and pulled out a bottle of headache medicine. She took two pills from it before putting it back into its place.

Before she could go back to recording the day's events in her journal, the metal front doors of her lab could be heard sliding open. She put her journal back into its hiding spot before standing up and going to the doors leading into her initial lab. "Hey," she said after seeing that her girlfriend had come over

Alphys didn't respond; it wasn't like she could. She still had on the muzzle she was required to wear out in public, which kept her from so much as even speaking. All she could do was nod in response.

"Come in, and you can take that dumb thing off," Undyne permitted. The two went inside of the lab and sat down together in some chairs nearby. Alphys ripped off the muzzle and crammed it into her pocket.

"I can hardly breathe with that stupid thing on," she muttered, her razor-like teeth gleaming as she spoke. "Well, you don't have to wear it around me," Undyne assured. Alphys nodded, then looked the fish in front of her over.

"New experiments? Those look like fresh blood stains on your coat," she noticed. Undyne looked down at the newly-acquired blood stains on her lab coat. "Yeah. I really need to put them under the next time I experiment, though. All of that screaming has given me a major headache. I'm still waiting for the medicine to kick in," she sighed.

Alphys had expected nothing less. Then, she noticed something else. "Handprints on your chest?" she asked. Sure enough, there were handprints of blood on Undyne's chest. She ran a hand through the base of her bun.

"Yeah. One of the experiments tried to use charm to get out of what was coming to him. When I told him that I'm not even interested in guys and that I had a girlfriend still, he just decided to go ahead and get all handsy with me. Needless to say, he was the first one to get his entrails carved out by my equipment," she recalled, a wicked grin adorning her features as she said the last part.

Alphys barked out a laugh. "That's my girl," she said. She pulled Undyne down by the front of her lab coat enough to give her a kiss on the mouth, nibbling on her bottom lip gently before pulling back. But, even a gentle nibble from razor teeth could puncture flesh.

Undyne wiped the blood from her wound. "Some call me crazy. I have no choice but to agree," she said.

Alphys nodded. Soon, her expression became more serious. "I want to do something with you. I want to mark you as mine...for good. I know just the way to do so," she said. Undyne raised an eyebrow. "Oh? And that way would be?" she inquired.

"Come on. Let's go to your room," Alphys said.

XxX

The girls stood together in the bedroom. "Now what?" Undyne asked. She was somewhat taken aback when Alphys unbuttoned her stained lab coat and tossed it to the floor, revealed her dark-red bra.

"Huh. And I always thought you wore something under that coat," she said. "Well, it's more or less a shirt. I never bothered with putting a tank-top or something on under it. What are you going to do to me to mark me as yours?" Undyne prodded. "Sit down. I'm shorter than I'd like to be," Alphys said.

She had always been annoyed by her height of four-feet-six-inches, but medical tests had claimed that she had one foot in the territory of mentally insane, hence why she had to keep a muzzle over her sharp teeth in public, so no one dared to crack a joke about her size.

Undyne sat down on the floor cross-legged. "Alright. Now what?" she asked. Alphys grinned darkly. "Bite marks."

She went over and slowly sank her teeth into Undyne's bare shoulder. She didn't pierce a hole through it, but she sank her teeth as far down as she could manage. The metallic taste of blood, after experiencing it time and time again, no longer had a repulsive effect on her. Rather, as the crimson flooded her mouth immediately, a chill of satisfaction was sent down her spine.

Undyne was shocked at first. She had been bitten before, but it had never been like this. Her shoulder wasn't completely bitten off, but she could feel something clamping at her bone. The pain had only lasted for a moment before she felt nothing. She half-smiled at the sensation; it was going to hurt a whole lot later, but that wasn't on her mind right now. For some reason, she was almost sad when she was released.

Alphys began to lap up the leaking blood from the wound, which wasn't too much. "That should scar pretty nicely. You're really mine now," she said. Blood was dripping down her face as she spoke and covering her jagged teeth.

"You might wanna wash your mouth out before you leave. People will think you killed someone," Undyne remarked. "Well, it won't be a first," Alphys shrugged. She wrapped her arms around her girlfriend's middle, smiling. Undyne reciprocated with her left arm only; her right shoulder was the one that had been bitten, so her right arm was currently out of use.

"I love you," she said quietly. "I love you too," Alphys responded. "This is really going to hurt later," Undyne commented, looking at her wound. "What can I say? Love hurts," Alphys said. "It really does, doesn't it?" Undyne asked rhetorically. She gave Alphys a long kiss on the mouth, tasting her own blood as she did so.

"You really are the romantic type. The willing and the hot type, too," Alphys said. Undyne leaned against her good arm. "Thank you. You know, you're pretty hot yourself," she replied. "Thanks. How about I match you?"

Before she could be asked what that meant, Alphys took off her t-shirt and tossed it onto the floor, revealing her black bra. "I don't think I can mark you like you can mark me. Although...I will certainly try," Undyne decided. "Go ahead. I'm ready," Alphys allowed.

Undyne moved even closer to her, slowly sinking her teeth into the dinosaur's shoulder. The blood that filled her mouth and dripped down her chin was a strange feeling at first. But quickly, she grew accustomed to it. Her bite wasn't close to matching the one she'd been given, yet she certainly tried. She released much quicker as well. True to what had been done to her, she lapped up the dripping blood, yet she wound up spitting it onto the floor of her room instead.

"I'll get that later. You're better suited for this kind of thing that I am," she admitted. "It's fine. Biting's my attack. Well...biting and using an axe, that is. You stick to using medical stuff. You seem to have fun," Alphys noted. "It's a lot of fun. Oh, the feeling is truly something," Undyne said. When she giggled maniacally at that, more blood dripped from her mouth and showed in her smile.

"Now you look like you helped me in the murder," Alphys added from the earlier statement. Undyne wiped someone of the blood that had fallen down her face onto her arm. "I guess so," she agreed. "Now I know how all of the people I've bitten have felt. Well...I sort of know how they felt," Alphys said.

Undyne stood up. "I hate to ruin the fun, but I'm gonna get this blood out of my mouth. And clean up this bite before it gets infected instead of scarred. I can handle seeing bloodbaths and getting it all over my clothes, but the taste is...bizarre. You might want to clean up as well," she suggested. She went to her bathroom and rinsed the blood from her mouth first, then cleaned up her wound. The antiseptic burned like lava, but it was hardly effective to her in that sense currently. She bandaged up her shoulder as well. "Now, you. Clean out your mouth. I'll clean up your wound and bandage it. It should scar fairly quickly," she assumed.

So, Alphys cleaned her mouth of the blood and got her injury tended to. "Thanks," she said once she had been taken care of. "I'm just trying to help. But I assume you don't want to leave just yet?" Undyne guessed. "Correct," Alphys confirmed. "And do you wanna...?" Undyne trailed off, knowing that her point was across without even having to say so. "Yep. We're together forever now. Might as well have some fun with it," Alphys reasoned.

So, she took Undyne's hand and lead her back to the bedroom.

XxX

Some time passed. the girls were laying together in bed, the only thing covering their bodies at this point being the blankets.

"This has been amazing," Undyne said honestly. "I wouldn't wanna spend time like this with anyone else," Alphys agreed. It was then that her cell phone rang. She groaned and got up to answer it. "Hello?" There was silence for a few moments. "Fine. I'll be there in a bit." Then, she hung up.

"What was that about?" Undyne inquired. "Gotta go. Royal Guard business," Alphys explained briefly. She put her clothes back on, as did Undyne. When they both were fully dressed again, they sat down on the bed.

"Put your glasses back on You look kinda weird without them," Alphys said. She tied her eyepatch back around her head and adjusted it to where it covered her useless eye. Undyne put her glasses back on, trying to adjust them to where they were straight while balancing on her ear fins. "Thanks for today," she said.

Alphys gave her one last kiss before reluctantly putting on her muzzle and leaving. Once she was alone, Undyne left her room and went back to her journal. She added one last thing to her entry

 _I am now Alphys' forever. And she is mine. Forever._

 *****And...that would be a that. To explain the muzzle thing, I've seen some fan art where Swapfell Alphys wears a muzzle and I decided to throw it in. Anyways, be sure to leave a review on the way out and I'll see you all in the next one! Bye!**


End file.
